Low specific contact resistance of heavily phosphorus-doped diamond film

Low resistive contacts were formed on heavily phosphorus-doped diamond (n+) films with phosphorus concentration of over ∼1020cm−3 grown on (111) diamond substrates by microwave plasma enhanced chemical vapor deposition with precise control of growth conditions. The specific contact resistance was determined by characterizing the current-voltage relations by means of transfer length method. It was found that the resistance of Ti∕n+ contact was significantly reduced down to the order of ∼10−3Ωcm2 even at room temperature, which indicates that the barrier width would be narrow for tunneling through the barrier to take place by heavy phosphorus doping.